Lake Forest police said Long was wearing orange running sunglasses and running shoes at the time of the incident. She was also wearing running pants, a t-shirt and a fleece jacket - all black.
As the investigation continues, detectives ask anyone who was at Forest Park Beach in Lake Forest on Thursday morning who may have seen Long to call the Lake Forest Police Department at 847-234-2601.
Long's body was recovered from the water by divers just before 11 a.m. Thursday and was transported to the coroner's office.
Lt. Brian Dykens said the U.S. Coast Guard was called to the scene around 8:30 a.m. after a 911 call reported a swimmer in distress. A number of emergency agencies from nearby communities also responded to the call.